qd_messenger.h

//C- -*- C++ -*-//C- -------------------------------------------------------------------//C- DjVuLibre-3.5//C- Copyright (c) 2002 Leon Bottou and Yann Le Cun.//C- Copyright (c) 2001 AT&T//C-//C- This software is subject to, and may be distributed under, the//C- GNU General Public License, either Version 2 of the license,//C- or (at your option) any later version. The license should have//C- accompanied the software or you may obtain a copy of the license//C- from the Free Software Foundation at http://www.fsf.org .//C-//C- This program is distributed in the hope that it will be useful,//C- but WITHOUT ANY WARRANTY; without even the implied warranty of//C- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the//C- GNU General Public License for more details.//C- //C- DjVuLibre-3.5 is derived from the DjVu(r) Reference Library from//C- Lizardtech Software. Lizardtech Software has authorized us to//C- replace the original DjVu(r) Reference Library notice by the following//C- text (see doc/lizard2002.djvu and doc/lizardtech2007.djvu)://C-//C- ------------------------------------------------------------------//C- | DjVu (r) Reference Library (v. 3.5)//C- | Copyright (c) 1999-2001 LizardTech, Inc. All Rights Reserved.//C- | The DjVu Reference Library is protected by U.S. Pat. No.//C- | 6,058,214 and patents pending.//C- |//C- | This software is subject to, and may be distributed under, the//C- | GNU General Public License, either Version 2 of the license,//C- | or (at your option) any later version. The license should have//C- | accompanied the software or you may obtain a copy of the license//C- | from the Free Software Foundation at http://www.fsf.org .//C- |//C- | The computer code originally released by LizardTech under this//C- | license and unmodified by other parties is deemed "the LIZARDTECH//C- | ORIGINAL CODE." Subject to any third party intellectual property//C- | claims, LizardTech grants recipient a worldwide, royalty-free, //C- | non-exclusive license to make, use, sell, or otherwise dispose of //C- | the LIZARDTECH ORIGINAL CODE or of programs derived from the //C- | LIZARDTECH ORIGINAL CODE in compliance with the terms of the GNU //C- | General Public License. This grant only confers the right to //C- | infringe patent claims underlying the LIZARDTECH ORIGINAL CODE to //C- | the extent such infringement is reasonably necessary to enable //C- | recipient to make, have made, practice, sell, or otherwise dispose //C- | of the LIZARDTECH ORIGINAL CODE (or portions thereof) and not to //C- | any greater extent that may be necessary to utilize further //C- | modifications or combinations.//C- |//C- | The LIZARDTECH ORIGINAL CODE is provided "AS IS" WITHOUT WARRANTY//C- | OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED//C- | TO ANY WARRANTY OF NON-INFRINGEMENT, OR ANY IMPLIED WARRANTY OF//C- | MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.//C- +------------------------------------------------------------------// // $Id: qd_messenger.h,v 1.7 2007/03/25 20:48:25 leonb Exp $// $Name: debian_version_3_5_21-3 $#ifndef HDR_QD_MESSENGER#define HDR_QD_MESSENGER#ifdef HAVE_CONFIG_H#include "config.h"#endif#if NEED_GNUG_PRAGMAS# pragma interface#endif#include "GThreads.h"#include "GContainer.h"#include "debug.h"#include "GURL.h"#include <qobject.h>// This class actually does synchronization between two threads by maintaining// a pipe and queue of messages. There can be just one queue per application// QDMessenger will be able to use the same queue as they provide their// address in every queue message so that the QDMessageQueue knows whom// to direct a message to.//// In some cases it's necessary to look ahead in the queue for other events// for the same QDMessenger. Here is an explanation "why"://// "It's important to do so at least for REDRAW events since usually// Decoder works pretty fast and manages to decode everything by the// moment when visualizer finishes redrawing the B&W picture. While// decoding the decoder sends a bunch of REDRAW requests thru this// messenger. Unfortunately, if we process it one-by-one then no event// compression will be observed as QT seems to pay much more attention// to XEvents (generated by x11Redraw) than to active SocketNotifiers.// Thus, instead of processing another pipe REDRAW command (and thus// sending another Expose event, which could be merged with the previous// one), QT notices Expose events returned from XServer and processes// it immediately. So we don't let QT return to event loop and do it.// We process all pending commands at once"//// So, there is a "look_ahead" setting for every QDMessenger, that the queue// may deal with. Every time when smth is read from the pipe, the queue// senses the QDMessenger which should take the message and, if look_ahead// is TRUE, it will look thru the queue for other messages for the same// QDMessenger until all of them are processed.class QDMessageQueue : public QObject
{
Q_OBJECT
public:
class Item
{
public:
Item * next;
class QDMessenger * messenger;
int cmd;
int req;
GUTF8String title, msg;
GUTF8String url, target;
Item(class QDMessenger * _messenger, int _cmd) :
next(0), messenger(_messenger), cmd(_cmd) {};
};
private:
int fd[2];
GCriticalSection queue_lock;
Item * queue_head;
private slots:
void notifierActivated(int);
public:
void addQueueItem(Item * item);
void doOneQueueItem(void);
void clearMessenger(class QDMessenger * messenger);
QDMessageQueue(QObject * parent=0, constchar * name=0);
virtual ~QDMessageQueue(void);
};
class QDMessenger : public QObject
{
Q_OBJECT
private:
// CMD_LAYOUT and CMD_REDRAW could have been implemented via// CMD_GENERAL_REQ as they don't require any arguments, but it's// nice to have these requests in separateenum CMD { SHOW_STATUS=0, LAYOUT, REDRAW,
SHOW_ERROR, GET_URL, GENERAL_REQ, GENERAL_MSG };
static QDMessageQueue * queue;
bool look_ahead;
signals:
void sigRedraw(void);
void sigLayout(void);
void sigShowError(constGUTF8String &, constGUTF8String &);
void sigShowStatus(const QString &);
void sigGetURL(constGURL & url, constGUTF8String &target);
void sigGeneralReq(int);
void sigGeneralMsg(constGUTF8String &);
public:
void showStatus(const QString &status);
void layout(void);
void redraw(void);
void showError(constGUTF8String &title, constGUTF8String &msg);
void getURL(constGURL & url, constGUTF8String &target);
void generalReq(int req);
void generalMsg(constGUTF8String &msg);
// Internal: called from QDMessageQueue::notifierActivated()void sendSignal(QDMessageQueue::Item * item);
void setLookAhead(bool la) { look_ahead=la; }
bool getLookAhead(void) const { return look_ahead; }
// The reason to pass parent here is to provide automatic destruction// of the messenger when parent passes away.// You may safely pass parent=0 if you don't forget to destroy the// messenger yourself
QDMessenger(QWidget * parent=0, constchar * name=0);
~QDMessenger(void);
};
#endif